The inclusion of lipase in detergent compositions for improved cleaning performance is known, e.g. enhancement of removal of triglycerides containing soils and stains from fabrics. Examples are U.S. Pat. No. 4,769,173; U.S. Pat. No. 5,069,809; PCT application WO94/03578.
In U.S. Pat. No. 4,769,173 is disclosed a certain class of lipases consisting of fungal lipases ex Humicola lanuginosa together with strong bleaching agents in detergent compositions. An example of a fungal lipase in this patent is the lipase ex Humicola lanuginosa, available from Amano under the tradename Amano-CE. In U.S. Pat. No. 5,069,809 is disclosed the combination of strong bleaching agents with a lipase enzyme produced by cloning the gene encoding the lipase produced by Humicola lanuginosa and expressing the gene in Aspergillus oryzae as host for use in detergent compositions. In WO 94/03578 is disclosed an enzymatic detergent composition containing 10 to 20 000 LU (Lipolytic units) per gram of detergent composition of a lipase showing a substantial lipolytic activity during the main cycle of a wash process. This lipase is selected in particular on its inactivation behaviour with Diisopropyl Fluoro Phosphate (DFP).
Of the lipase enzymes, only the lipase derived from Humicola lanuginosa and produced in Aspergillus oryzae as host has so far found wide-spread application as additive for fabric washing products. It is available under the tradename Lipolase.RTM., from Novo Nordisk.
In order to optimize the stain removal performance of Lipolase, Novo Nordisk have made a number of variants. WO 92/05249 describes the D96L variant of the native Humicola lanuginosa lipase improves the lard stain removal efficiency by a factor 4.4 over the wild-type lipase (enzymes compared in an amount ranging from 0.075 to 2.5 mg protein per liter).
The ability of lipase to clean soils and stains from fabrics present in the typical load of laundry is of high importance in the evaluation of detergent performance. Unfortunately, the relative ability of lipase to meet various performance criteria is among other depending on the presence of cosurfactants.
There is thus a standing desire for performance and flexibility reasons to make available a surfactant system capable of providing optimum detergency performance of the lipase.
The above objective has been met by a surfactant system comprising a cosurfactant selected from the group of primary or tertiary amines.
It has been surprisingly found that the inclusion of specially selected primary or tertiary amines into liquid detergent compositions containing a lipolytic enzyme (lipase) substantially enhances their ability to rapidly lower the interfacial tension of aqueous washing liquors containing greasy and oily soils. This substantial reduction of interfacial tension of greasy and oily soils improves their removal from soiled surfaces and inhibits the redeposition of the soils onto substrates.
It has also been surprisingly found that liquid detergent compositions containing a lipolytic enzyme and a specially selected primary of tertiary amine show synergistic removal of greasy/oily soils particularly when the detergent composition is used in a pre-treatment application to greasy/oily soil stains on fabrics prior to and in conjunction with a normal wash process of the fabrics.